The present invention relates to checkerboard type color encoding filters, and more particularly, to such filters when used with cameras having an array of discrete sensors such as a CCD (charge coupled device) having interlaced scan.
It is known to use checkerboard color encoding filters with cameras having single CCD imagers, such as is disclosed in U.S. Patent application No. 094,286, filed Nov. 19, 1979 (RCA 74,184) in the name of R. Rhodes. With such a filter, it is necessary that the registration of the checkerboard with respect to the photosensors on the CCD be essentially perfect, especially with regard to parallelness of the horizontal lines. If there is an error in the parallelness, the amount of a particular color over a discrete photosensor will change across a horizontal line, resulting in a color shift error when scanning, which is difficult to compensate. Further, if interlaced scan is used, the amount of color error due to said nonparallelness varies between the two interlaced fields. This results in 30 Hertz flicker in the color error when using an NTSC scanning standard.
It is therefore desirable to have a color filter which eliminates color shift and flicker problems.